- Joined
- Dec 14, 2013
- Messages
- 397
Hi
I needed a new front disc for my 1972 Norton, so did a search and came up with a disc from India for $79 AU, thought I may give it a go.
It looked real good by eye, I fitted this week, but it started to lock up when I offered up the axle, the disc was binding on the side of the caliper :shock:
I removed it and got the measuring gear out and found a couple of things, the inner flange (with the bolt holes) was .024" too thick and the disc was 0.033" too thick.
So into the lathe, made up a mandrel and turned the mating face down to the same as my original disc, this moved the disc away from the caliper, I then machined the outer face of the disc to bring it on size and away from the caliper, what I found was the disc was tapered thick on the outer and thin towards the centre, also the disc had high spots, probably should have binned it at this stage, once I got it machined flat and true I then faced the inner side of the disc it was much the same as the back face, in the end it all worked, with disc central in the caliper and brakes are good again.
The lesson here is I should have not been such a tight "A" and spent a bit extra from a known supplier, where I could have at least sent it back for replacement one.
It is a shame but the appearance/finish of the disc looked very good, cannot work out why it was machined so far out of tolerance, only thing I could think of was it must have been moving while it was being machined? :shock:
Burgs
I needed a new front disc for my 1972 Norton, so did a search and came up with a disc from India for $79 AU, thought I may give it a go.
It looked real good by eye, I fitted this week, but it started to lock up when I offered up the axle, the disc was binding on the side of the caliper :shock:
I removed it and got the measuring gear out and found a couple of things, the inner flange (with the bolt holes) was .024" too thick and the disc was 0.033" too thick.
So into the lathe, made up a mandrel and turned the mating face down to the same as my original disc, this moved the disc away from the caliper, I then machined the outer face of the disc to bring it on size and away from the caliper, what I found was the disc was tapered thick on the outer and thin towards the centre, also the disc had high spots, probably should have binned it at this stage, once I got it machined flat and true I then faced the inner side of the disc it was much the same as the back face, in the end it all worked, with disc central in the caliper and brakes are good again.
The lesson here is I should have not been such a tight "A" and spent a bit extra from a known supplier, where I could have at least sent it back for replacement one.
It is a shame but the appearance/finish of the disc looked very good, cannot work out why it was machined so far out of tolerance, only thing I could think of was it must have been moving while it was being machined? :shock:
Burgs